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At least 199 records · Page 11Linked to original sources
PubMedDate not supplied

[Muscarinic acetylcholine receptors in peripheral human lung tissue: binding characteristics of 3H-quinuclidinyl-benzilate in malignancies].

Binding of muscarinic receptors antagonist 3H-quinuclidinyl benzylate (3H-QNB) was studied in human peripheral lung tissue, obtained after resection of pulmonary carcinoma and partial resection of tuberculoma from surrounding normal tissues (control group). Radioligand binding assays showed that binding of 3H-QNB in lung parenchyma membranes of both normal, healthy persons and patients with cancer was saturable with high rate of affinity. Saturation occurred at 1 nm concentration of the ligand. The Scatchard plot analysis indicated that the high affinity binding site exhibited the following parameters: Kd = 0.33 nm, Bmax = 164.8 fmol/mg in the group of controls: and Kd = 0.63 nm, Bmax = 401.5 fmol/mg in the group of patients with cancer. Maximal amount of 3H-QNB binding sites was distinctly increased in malignization of peripheral lung tissue. The results obtained suggest that increase in concentration of 3H-QNB binding sites may be among the specific patterns of malignant growth in lung peripheral tissue.

Binding Sites↗
PubMedDate not supplied

[The specific binding of dihydroalprenolol and quinuclidinyl benzilate with myocardial lysosomes].

The binding of 3H-dihydroalprenolol and 3H-quinuclidinyl benzylate to lysosomes of the rat ventricular myocardium vas studied. More than one type of specific binding sites of dihydroalprenolol and quinuclidinyl benzylate at the rat myocardium lysosomes were found. The association constants values differ from the known values of the association constants of the same ligands with plasmatic membranes of the mammalian myocardium.

Alprenolol↗
PubMed1986

[3H]pirenzepine and (-)-[3H]quinuclidinyl benzilate binding to rat cerebral cortical and cardiac muscarinic cholinergic sites. I. Characterization and regulation of agonist binding to putative muscarinic subtypes.

The binding and regulation of selected muscarinic agonists to putative subtypes in rat cerebral cortex and heart were studied. Parallel inhibition studies of [3H]pirenzepine ([3H]PZ) and (-)-[3H]quinuclidinylbenzilate [(-)-[3H]QNB]-labeled membranes were done with and without 30 microM guanyl-5'-yl imidodiphosphate [Gpp(NH)p] at 25 degrees C in 10 mM Na-K-phosphate buffer which enhances PZ binding affinity and in modified Krebs-phosphate buffer, which mimics physiological conditions. Classical agonists such as carbachol, oxotremorine and acetylcholine inhibited (-)-[3H]QNB binding to membranes with shallow Hill values (nH less than 1), were better fit to a 2-state model, were Gpp(NH)p-regulated and showed lower affinity in modified Krebs-phosphate buffer than in 10 mM Na-K-phosphate buffer. Some agonists were not significantly better fit to a 2-state model in [3H]PZ-labeled cortical membranes, especially in 10 mM Na-K-phosphate buffer. Whereas putative M1 and M2 binding sites distinguished by PZ possessed multiple agonist affinity states, as judged by carbachol, and agonist binding to [3H]PZ-labeled sites were Gpp(NH)p modulated, the partial agonist pilocarpine and nonclassical agonist McN-A-343 [3-(m-chlorophenylcarbamoyloxy)-2-butynyl trimethylammonium chloride] showed little Gpp(NH)p-induced shift in [3H]PZ-labeled cortical membranes in physiological conditions. Agonist binding to (-)-[3H]QNB-labeled putative M2 cardiac sites was more sensitive to Gpp(NH)p than (-)-[3H]QNB-labeled cortical sites. Carbachol and acetylcholine showed significant selectivity for putative M2 sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1986

[3H]pirenzepine and (-)-[3H]quinuclidinyl benzilate binding to rat cerebral cortical and cardiac muscarinic cholinergic sites. II. Characterization and regulation of antagonist binding to putative muscarinic subtypes.

Studies show [3H]PZ identified selectively a subpopulation of muscarinic binding sites compared to classical antagonists like (-)-[3H]QNB in many central and peripheral tissues. We characterized the binding and regulation of selected antagonists to high-affinity [3H]PZ (putative M1) and low-affinity PZ (putative M2) sites in rat cerebral cortex (predominantly M1) and heart (predominantly M2). Saturation isotherms of [3H]PZ and (-)-[3H]QNB were performed under various conditions. Guanyl-5'-yl-imidodiphosphate (30 microM) showed little effect on Kd (dissociation constant) or total binding capacity (total receptor density) values. Higher ionic strength buffers yielded lower affinity values for [3H]PZ and (-)-[3H]QNB. Kinetic studies confirmed high affinity Kd values seen in steady-state assays. We conducted inhibition studies of selected muscarinic antagonists including the reportedly cardioselective (putative M2) drug, AF-DX 116 (11-[(2-(diethylamino)methyl-1-piperidinyl)-acetyl]-5, 11-dihydro-6H-pyrido(2,3-b)(1,4)-benzodiazepine-6-one], the reportedly M1 selective compound, PZ, and the classical antagonist (-)QNB, using [3H]PZ and (-)-[3H]QNB-labeled cerebral cortical and cardiac homogenates. Assays were done with and without guanyl-5'-yl-imidophosphate at 25 degrees C in 10 mM Na-K-phosphate, 50 mM Na-K-phosphate and modified Krebs-phosphate buffer. Studies showed antagonists generally had higher affinity in 10 mM Na-K-phosphate buffer, were insensitive to guanyl-5'-yl imidodiphosphate and had Hill values (nH) nearly equal to one. Cardiac PZ/[3H]QNB curves were steep.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗